Software upgrade may have caused triple-0 delays

An upgrade of Victoria's emergency call service may have contributed to delays on the triple-0 line during Wednesday night's freak storm.

Emergency Services Commissioner Bruce Esplin said callers waited between eight seconds and 41 minutes for a response on the triple-0 line at the height of the storm.

Mr Esplin said a software upgrade was delayed because of early storm warnings but after receiving new advice from the weather bureau at 8.30pm (AEDT) the upgrade went ahead at 9pm.

However, Emergency Communications Victoria employed more staff to account for the slowdown of the system which would go into manual mode during the upgrade, he said.

But when another extreme thunderstorm warning came through at 11.50pm, it was too late to unload what had started and reinstall the old system.

"If anything, there was only a very minor contribution to call answering delays by the software upgrade," Mr Esplin told ABC radio.

"All attempts were in place to make sure it was done responsibly and without risk to public safety or degradation of call times."

Mr Esplin said the level of help needed was higher than could have possibly been predicted.

"I think the issue is simply the sheer size and scale of the event," he said.

"It was unprecedented and by our analysis of all the data it was five to six times greater than any extreme event call-taking volume ever created before."

The number of calls on Wednesday night were 17 times the average for that time of day, he said.

"It was a freak weather event and I don't think any organisation would ever staff up to the level to handle that," Mr Esplin said.

He said less than 30 callers waited longer than 10 minutes for their calls to be answered and the average wait-time was about two minutes.

"Given the sheer scale of the event I think that's probably a very good performance."

The service was criticised in federal parliament yesterday after a Canberra family's house burnt down when the occupants were unable to get through on the congested triple-0 emergency line to report the fire.